Allow to limit zed's syslog chattiness

Some usage patterns like send/recv of replication streams can
produce a large number of events. In such a case, the current
all-syslog.sh zedlet will hold up to its name, and flood the
logs with mostly redundant information. Two mitigate this
situation, this changeset introduces to new variables
ZED_SYSLOG_SUBCLASS_INCLUDE and ZED_SYSLOG_SUBCLASS_EXCLUDE
to zed.rc that give more control over which event classes end
up in the syslog.

Reviewed-by: loli10K <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Giuseppe Di Natale <[email protected]>
Signed-off-by: Tony Hutter <[email protected]>
Signed-off-by: Daniel Kobras <[email protected]>
Closes #6886 
Closes #7260 

1 files changed, 20 insertions, 0 deletions

diff --git a/cmd/zed/zed.d/zed-functions.sh b/cmd/zed/zed.d/zed-functions.sh
index ed6a95914..fb16e9d36 100644
--- a/cmd/zed/zed.d/zed-functions.sh
+++ b/cmd/zed/zed.d/zed-functions.sh
@@ -438,3 +438,23 @@ zed_guid_to_pool()
 		$ZPOOL get -H -ovalue,name guid | awk '$1=='"$guid"' {print $2}'
 	fi
 }
+
+# zed_exit_if_ignoring_this_event
+#
+# Exit the script if we should ignore this event, as determined by
+# $ZED_SYSLOG_SUBCLASS_INCLUDE and $ZED_SYSLOG_SUBCLASS_EXCLUDE in zed.rc.
+# This function assumes you've imported the normal zed variables.
+zed_exit_if_ignoring_this_event()
+{
+	if [ -n "${ZED_SYSLOG_SUBCLASS_INCLUDE}" ]; then
+	    eval "case ${ZEVENT_SUBCLASS} in
+	    ${ZED_SYSLOG_SUBCLASS_INCLUDE});;
+	    *) exit 0;;
+	    esac"
+	elif [ -n "${ZED_SYSLOG_SUBCLASS_EXCLUDE}" ]; then
+	    eval "case ${ZEVENT_SUBCLASS} in
+	    ${ZED_SYSLOG_SUBCLASS_EXCLUDE}) exit 0;;
+	    *);;
+	    esac"
+	fi
+}